The present invention concerns blend compositions comprising asphalt or bitumen modified with interpolymers of olefins and vinylidene aromatic monomers applicable to paving, roofing and other construction materials containing these compositions, a process for preparing said compositions and the composition of the interpolymers used to make the blended compositions. The invention also concerns new substantially random interpolymers resulting from polymerizing at least one olefin, at least one vinylidene aromatic monomer and at least one diene.
The use of petroleum residuum such as asphalt as a paving material and other construction material is well known. It is also well known to blend various polymeric materials into the asphalt to improve certain properties. For example, polyolefins have been used; but, as pointed out in U.S. Pat. No. 4,240,946 the teachings of which are specifically incorporated herein by reference, the addition of such polyolefins increases the viscosity of such blends at working temperatures thus necessitating special mixing and homogenizing procedures. The use of such polyolefins, however, is greatly desired since they help maintain the integrity of the asphalt when subjected to elevated temperatures such as when used as paving, roofing or other construction material. It would be desirable if a material were discovered which when added to bitumen would broaden the applicable temperature range of bitumen, stiffening the bitumen at high temperatures while maintaining low temperature flexibility and usable viscosities. It would also be desirable if this additive would be stable to the high temperatures encountered during the blending with bitumen and long term storage of the blend.
It would be highly desirable if polymers were available which were compatible with a variety of asphalt compositions and it would further be desirable if these polymers were easily mixed into the asphalt with only low shear agitation.